The Venus Transit of June 8, 2004, 6.19 BST to 12.24 BST,
as observed from the University of Sussex
by (Klaus-) Peter Schroeder
Not only was the UK in a favourable place to observe
this first Venus transit after 122 years, there was even a lot of
sunshine in the southeast of england! Only a few cirrus clouds
brightened the background during the egress at midday. Here, at the
University of Sussex Astronomy Centre, students and staff gathered
between lecture hours to observe the event.
This webpage gives a small selection of the photos taken by us
at the Astronomy Centre (SciTech), from on-campus.
The two photos above have been taken during ingress in the morning hours,
with the Sun still low in the eastern sky, with a small 80/600mm portable
refractor from the upper Art's parking lot. The effects of atmospheric
turbulence (seeing) are quite obvious. Still, the deliberately
overexposed photo of the ingress in progress shows a subtle arc of
light along Venus outer edge. This is evidence for the atmosphere
of Venus which here refracts the sunlight from behind. The second
photo, taken just after ingress was completed, shows the "back drop"
effect, mainly caused by image degradation in bad seeing
(compare with the photo below at egress, 3rd contact, in better seeing!).
A digital camera (Camedia 4040) was used, held behind a 4mm eyepiece and
with a total filter factor of about 10,000 to 1, set at 100 ASA,
exposure time 1/800 sec.
The above two photos show the progress of Venus' transit during the
later morning hours. These are coloured B&W images, taken with a 100mm f/15
refractor, with 3m focal length, on the special ultra-fine-grain, high-contrast
film Agfa Ortho 25 (1/2000 sec exposure with special 1:650 front-lens filter).
The image at left is just a much enlarged section around
the disk of Venus from the second-last image above. The special
film captured remarkable solar surface detail (the Granulation, which are
the huge bubbles in the boiling solar surface),
hardly visible to the visual observer. Compare with the professional
photo of a >10x larger (!) telescope on a mountain site, below
(last photo on this page). -
Sussex does not do so bad, after all.....
The two photos above where taken during egress just after noon.
While contrast then suffered from thin cirrus clouds, the seeing
was much better. With the use of a larger (100/1500mm) telescope,
a higher resolution was achieved, but the arc of light from the
Venus atmosphere is almost lost in the bright background. The same digital
camera and filtering was used as above, but with a 10mm eyepiece.
And this is what the powerful Swedish Solar Telescope saw under the
clean skies of of the LaPalma Observatory on Roque de los Muchachos,
at an elevation of 7300ft. The atmospheric glow at Venus' outer limb
is very clearly visible.
Last update: June 16, 2004
Author: Klaus-Peter Schroeder,
e-mail to: email@example.com